Fig. 3
![Fig. 3](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40168-015-0108-3/MediaObjects/40168_2015_108_Fig3_HTML.gif)
Principal coordinate analysis (PCoA) of bacteria in the 16 “sink” studies in this meta-analysis. Communities are compared using the unweighted UniFrac distance metric. a Studies cluster generally by study identity, and the top ten indicator taxa (triangles) are indicative of human-associated bacteria as well as outdoor-derived taxa. b Bacterial community composition also tend to group by the matrix type (the physical sample type) as well as the way the building is used (c)